This invention generally relates to a dilatation catheter for angioplasty procedures such as percutaneous transluminal coronary angioplasty (PTCA).
In PTCA procedures, a dilatation catheter having an inflatable, relatively inelastic balloon on the distal end thereof is advanced through a patient's arterial system until the balloon crosses the atherosclerotic lesion to be dilated. The balloon is inflated to a predetermined size with radiopaque liquid at relatively high pressures (e.g., atmospheres) to dilate the stenotic region and then the balloon is deflated so that the catheter can be removed and blood flow resumed at a higher flow rate due to the expanded diameter of the stenotic region.
Typically a guiding catheter having a preformed distal end is first percutaneously introduced into the patient's arterial system and advanced until the distal tip of the guiding catheter is disposed in the appropriate ostium of the patient's coronary artery. A guidewire is slidably disposed within an inner lumen of a dilatation catheter and both are advanced through the previously positioned guiding catheter to the distal end thereof. The guidewire is first advanced out of the guiding catheter into the patient's coronary anatomy until the distal end of the guidewire crosses the stenotic region to be dilated. The physician usually shapes the distal end of the guidewire to facilitate steering it through the patient's coronary arteries. Once the guidewire is in place, the dilatation catheter is then advanced over the guidewire until the inflatable balloon is positioned within the stenosis. The balloon is inflated to a relatively high pressure to dilate the stenosis and then deflated and removed over the guidewire. For a detailed description of procedures, reference is made to U.S. Pat. No. 4,332,254 (Lundguist), U.S. Pat. No. 4,323,071 (Simpson-Robert), U.S. Pat. No. 4,439,185 (Lundguist), U.S. Pat. No. 4,468,224 (Enzmann et al.), U.S. Pat. No. 4,516,972 (Samson), U.S. Pat. No. 4,538,622 (Samson et al.), U.S. Pat. No. 4,554,929 (Samson et al.), U.S. Pat. No. 4,569,347 (Frisbie), U.S. Pat. No. 4,571,240 (Samson et al.), U.S. Pat. No. 4,638,805 (Powell), U.S. Pat. No. 4,748,982 (Horzewski et al.), all of which are hereby incorporated herein in their entirety by reference thereto.
The prior art has shown dilatation and other intravascular catheters which perfuse blood through the interior of a balloon when the balloon is inflated during angioplasty or other intravascular procedure in order to avoid ischemic conditions distal to the inflated balloon during the procedure. For example, intravascular catheters providing perfusion capabilities are described in U.S. Pat. No. 3,834,394 (Hunter et al), U.S. Pat. No. 4,423,725 (Baran et al.) and U.S. Pat. No. 4,790,315 (Mueller, Jr. et al.) which are incorporated herein by reference thereto. See also, U.S. Pat. No. 4,581,017 (Sahota). However, the catheters described in these references rely on the natural blood flow through the artery to perfuse blood through the balloon and distal to the catheter and as a result these catheters do not always provide sufficient blood to tissue distal to the catheter to completely avoid ischemic conditions, particularly with long term dilatation, e.g. an hour or more.
Gruntzig et al. in U.S. Pat. No. 4,195,637 describes pumping blood from an extracorporeal source through the inner lumen of a dilatation catheter. In the catheter system described, the blood is delivered through the proximal end of the catheter in a construction which would require the complete removal of the guidewire when perfusing blood. However, complete removal of the guidewire while the catheter remains within the stenosis is not very desireable from a clinical point of view.
What has been needed and heretofore unavailable is a perfusion-type dilatation catheter which can easily and quickly perfuse blood distal to the catheter with sufficient pressure and flow rate to avoid ischemic conditions distal to the catheter. The present invention satisfies this need.